6-(Trifluoromethyl)-2H-pyran-2-ones: Promising CF3-bearing conjugated cyclic diene and electrophilic building-blocks

• It was shown that 6-CF3-2-pyrones are promising CF3-bearing building-blocks.
• 6-CF3-2-pyrones reacted as conjugated cyclic dienes.
• 6-CF3-2-pyrones reacted as conjugated electrophiles.
• Trifluoromethylated cycloadducts were synthesized from 6-CF3-2-pyrones.
• Trifluoromethylated 1,2,3-triazoles were synthesized from of 6-CF3-2-pyrones.

This review describes synthetic methods for the preparation of such advanced conjugated cyclic dienes and electrophiles as 6-CF3-2-pyrones (6-(trifluoromethyl)-2H-pyran-2-ones), their versatile chemical properties and use in the syntheses of various CF3-containing cycloadducts, highly functionalized trifluoromethylated aromatic and heteroaromatic compounds. Synthesis of 6-CF3-2-pyrones bearing a substituent (substituents) at position(s) 3, 4 and 5, regio- and stereoselective preparation of trifluoromethylated cycloadducts (and their derivatives) via Diels–Alder reactions (and retro hetero–Diels–Alder reaction) from these pyrones and compounds containing in their molecules a reactive double (triple) bond, as well as reactions with nucleophiles has been presented in the review. Due to the presence of the electron-withdrawing trifluoromethyl group and the diene moiety, 6-CF3-2-pyrones are highly reactive substrates towards both dienophiles and nucleophiles. High regio- and stereoselectivity of the reactions allows the use of these excellent CF3-containing building-blocks for the preparation of various bicyclic, aromatic and heteroaromatic compounds, important starting substrates in biological or medicinal chemistry and related areas.

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